In recent years, downsizing and weight saving of portable electronic devices typified by a mobile phone, a PDA (personal digital assistant), and a notebook personal computer have been actively promoted. As part thereof, the energy density of batteries, in particular the secondary batteries as the driving power source thereof has been strongly aspired. As a secondary battery capable of providing the high energy density, for example, lithium ion secondary batteries using a material capable of inserting and extracting lithium (Li) such as a carbon material for the anode are known.
Further, in recent years, as a secondary battery capable of providing the high energy density, a secondary battery in which a material capable of inserting and extracting lithium is used for the anode, a lithium metal is precipitated on the surface, and thereby the capacity of the anode includes the capacity component due to insertion and extraction of lithium and the capacity component due to precipitation and dissolution of lithium has been developed (for example, refer to Patent document 1).
In these secondary batteries, for example, a secondary battery in which a complex oxide containing lithium, cobalt (Co), manganese (Mn) or the like is used for the cathode, and a solvent such as ethylene carbonate and an electrolyte salt such as lithium phosphate hexafluoride are used for the electrolytic solution has been practically used.
Patent document 1: International Publication No. 01/22519
Patent document 2: Japanese Unexamined Patent Application Publication No. 7-31227
Patent document 3: Japanese Unexamined Patent Application Publication No. 10-177814